A series of investigations are proposed to examine the cardiovascular and renal control by the normothermic and hibernating marmot. Using chemically catheterized preparations these studies will include: continuous blood pressure recording during the phases of induction, hibernation and arousal, the influence of autonomic drugs and angiotensin on cardiovascular responses of normothermic and hibernating animals, cardiac output during normothermia and hibernation, estimation of fluid compartments and constituents during normothermia and hibernation, and adrenal and posterior pituitary influences on electrolyte and water metabolism during hibernation and normothermia.